Image display

ABSTRACT

Apparatus for displaying an image comprises a liquid crystal display  12 , a lenticular lens array  14  for directing different portions of the image in different directions and mirrors  16  for reflecting at least some of the directed image, to produce an effective image  18  larger than the original image. The apparatus can be a mobile phone  10  or a visual display unit.

This invention relates to an apparatus and a method for displaying animage. In particular it relates to an apparatus and method for producingan effective image that is larger than the generated image.

Portable communication devices, for example, mobile phones areincreasingly popular. However, while on the one hand there is a desireto miniaturise the device to increase its portability, there is acompeting desire to increase the functionality of the device byincluding such features as video telephony and internet browsingcapabilities. For a user to derive the greatest benefit from theseadditional features, a suitably large display is required, whichconflicts with the desire to miniaturise the device. A different butrelated problem also occurs in small office spaces where it is oftendesirable to have a much larger display screen area than is possibleowing to the physical constraints of the desk and cubicle.

U.S. Pat. No. 5,305,124 discloses a virtual image display system fordisplaying a relatively large virtual image to a user derived from arelatively small image source. A lens group is provided for amplifyingan image provided by the image source. A plurality of reflectingelements are provided for magnifying the image provided by the lensgroup and for displaying the relatively large virtual image. The imageprovided by the image source is amplified through a lens groupcomprising at least two optical lenses and is then magnified by firstand second reflecting mirrors to project a large screen image to a user.The system may also include a window element, typically configured inelliptical shape, to minimise ambient reflection observed by the user.The system of this Patent is a projection system and does not provide asolution for direct viewing of, for example, a mobile communicationdevice.

It is therefore an object of the invention to provide an improveddisplay apparatus and method.

According to a first aspect of the present invention, there is providedapparatus for displaying an image comprising image generating means,image directing means for directing a first portion of the image in afirst direction and for directing a second portion of the image in asecond direction, and image reflecting means for reflecting at leastsome of said second portion, operable to produce an effective imagelarger than said image generating means.

According to a second aspect of the present invention, there is provideda method for displaying an image comprising generating an image,directing a first portion of the image in a first direction, directing asecond portion of the image in a second direction, and reflecting atleast some of the second portion, thereby producing an effective imagelarger than the generated image.

Owing to the invention, it is possible to provide an effective imagethat is larger than the generated image, but without requiring anyprojection onto a screen, so that the user can view the effective imagedirectly from the device. A display of a given physical area can be usedto present a significantly larger effective image to the user.

To view the whole of the effective image, the user may need to movetheir head relative to the image generating means so that they arelooking towards the image reflecting means. This depends upon theposition of the user's eye relative to the apparatus. When the user'seye is close to the apparatus the whole of the effective image can beseen directly. In this way a user can view all of the different parts ofthe effective image. The whole of the image can be considered to bementally present.

Advantageously the image generating means comprises a liquid crystaldisplay or an array of light emitting diodes. The image directing meanspreferably comprises a lenticular lens array or an array ofsubstantially spherical lenses overlying said image generating means.Alternatively said image generating means and said image directing meansmay comprise an array of directional light sources.

The image reflecting means advantageously comprises first and secondelements located at respective opposite sides of said image generatingmeans, and desirably located at substantially all sides of said imagegenerating means. In a preferred embodiment, the image reflecting meanscomprises a mirror.

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying drawings, in which:—

FIG. 1 a is a front view of a mobile communication device,

FIG. 1 b is a front view of the mobile communication device of FIG. 1 ashowing a mental perception of an effective image,

FIG. 2 is a partial section along the line II-II of FIG. 1 b,

FIG. 2 a is a more detailed view of FIG. 2,

FIG. 3 a is a view of an effective image,

FIG. 3 b is a view of image generating means of the mobile communicationdevice,

FIG. 4 is a perspective view of a visual display unit,

FIG. 5 is a partial front view of a second embodiment of the imagedirecting means,

FIG. 6 is a front view of a second embodiment of the mobilecommunication device showing a mental perception of an effective image,and

FIG. 7 is a partial section of another embodiment of the imagegenerating means and image directing means.

In FIGS. 1 a, 1 b and 2, a mobile communication device in the form of amobile phone 10 is shown. The phone 10 includes image generating meansin the form of a liquid crystal display 12 and image directing means inthe form of a lenticular lens array 14 overlying the image generatingmeans. The phone 10 also includes image reflecting means. The imagereflecting means comprises first and second elements in the form ofmirrors 16, located at respective opposite sides of the image generatingmeans. The image reflecting means can be a curved, multi-facet orsawtooth mirror, or any reflective surface.

The phone 10 also includes conventional components and featuresincluding an aerial, keypad, microphone, speaker etc., not shown forreasons of clarity. FIG. 1 b shows the phone 10 when the power is on andthe phone 10 is producing an effective image 18 larger then the originalimage.

FIG. 2 shows, in more detail, the working of the apparatus fordisplaying an image. FIG. 2 is not to scale, in order to facilitateunderstanding of the apparatus. For example, the lenticular lens array14 is shown much larger than it is in reality. The lens array 14comprises a large number of small lenses that extend from top to bottomof the array and are semi-cylindrical in cross-section. Such lenses arewell known in the field of autostereoscopic displays, described in, forexample, U.S. Pat. No. 6,064,424 and U.S. Pat. No. 6,118,584,incorporated herein by reference.

The liquid crystal display 12, in this arrangement, has three pixelsacross the width of each lens of the array 14. The light emitted by eachpixel travels in a straight path through the lens overlying it and isthen directed on exit by the curvature of the lens surface. Thesubsequent paths of the light of each set of three pixels are shown forone set of three in FIG. 2. The paths shown represent the centre line ofa conical fan of light that is produced by each lens/pixel combinationof the array 14.

The conical fans are illustrated in FIG. 2 a, for clarity purposes,showing only the fans 20′ and 22′. The fan 22′ is directed in a forwardsdirection, and the fan 20′ is directed in a sideways direction to bereflected by the mirror 16.

The paths 20, 22 and 24 are followed by all of the pixels in that columnof the display 12. The light from the columns of three pixels underneatheach other lens is directed in the three different directions in thesame respective manner. The net result of this is that the imageproduced by the image generating means is directed by the imagedirecting means, with a first portion of the image travelling in a firstdirection, a second portion of the image travelling in a seconddirection and a third portion travelling in a third direction.

The light on the path 22 and all of the light emitted from the pixelsbeing similarly directed in a forward direction combine to create thecentral part of the effective image 18. While only one third of thepixels in the display 12 are used to create this part of the effectiveimage 18, as long as the display 12 is of sufficiently high resolution,a perfectly acceptable effective image 18 is produced.

The path 20 illustrates the path of the light emitted from the column ofpixels that are directed by the lens to one side, at an angle to thehorizontal. The value of the angle depends upon the exact position ofthe pixel relative to the lenticular lens and also on the shape of thelens curve. A portion of the totality of the light that is directedtoward the one side is reflected by the mirror 16. In FIG. 2 this mirror16 is shown as being at 90 deg to the display 12 and lens array 14, butthe mirror could equally well be placed at an angle off theperpendicular, sloping outwards. In some applications this may, in fact,be preferable.

The portion of the image from the display 12 that is reflected by themirror 16 creates a portion of the effective image 18 to one side of thecentral part. This side portion of the effective image 18, in mostpositions of the user's eye 15, is visible to the user of the phone 10when the phone 10 is tilted so that the user is looking more towards themirror 16. The pixel A is seen by the user as if it is at the point A′.If the user's eye 15 is close to the phone 10 (as in FIG. 2), then bothof the central and side parts of the effective image will be seen,without any need to tilt the phone.

At the opposite side of the display 12, a portion of the totality of thelight that is directed toward the second side of the display 12 isreflected by the mirror 16 on that side of the display. This light thatis reflected by the mirror 16 creates the other side of the effectiveimage 18. In this manner the effective image 18 is built up from threediscrete portions of the original image produced by the display 12.

The actual rays seen by the user's eye depends upon the position of thephone 10 relative to the user. Since each pixel produces a cone of light(as shown in FIG. 2 a), as long as the user's eye is within the conethey will receive a ray of light from that pixel.

In order to produce the effective image 18, it is necessary to carry outa certain amount of image processing to ensure that the pixels in thedisplay 12 are addressed correctly to produce the final effective image18. This is illustrated in more detail in FIGS. 3 a and 3 b (shown toscale). The effective image 18 of FIG. 3 a is to be shown by the phone10 having a liquid crystal display 12 as in FIG. 3 b. The centralportion C of the effective image 18 is mapped to the central columns ofeach set of three columns of pixels across the entirety of the display12, reducing its resolution by two thirds. The left hand portion L ofthe effective image 18 is mapped in reverse to the left hand columns ofeach of the set of three columns of pixels in the portion L′ of thedisplay 12 of FIG. 3 b, again reducing its resolution by two thirds. Theright hand portion R of the effective image 18 is mapped in reverse tothe right hand columns of each of the set of three columns of pixels inthe portion R′ of the display 12 of FIG. 3 b, also reducing itsresolution by two thirds. This image processing produces the correcteffective image 18, once the lenticular lens array 14 and mirrors 16have directed and reflected the particular portions of the originalimage produced by the display 12.

FIG. 4 shows a visual display unit 30, with the lenticular lens array 14overlying the liquid crystal display 12. The display unit 30 is providedwith mirrors 16. When the unit 30 is in power on mode, an effectiveimage is produced that is larger than the original image from thedisplay 12, in the same manner as described for the phone 10 of FIGS. 1a, 1 b and 2. The user of such a unit 30 therefore has an effectiveimage larger than the screen of the unit 30 and can, even if working ina relatively confined space, derive the advantage of such an enlargedeffective image. For example, at the left hand side of the unit 30 theeffective image will extend over the partition screen 32 to createuseful extra display space.

FIGS. 5 and 6 relate to a second embodiment of the display apparatus ofthe mobile phone 10. In this embodiment, the image reflecting means (inthe form of a mirror 40) is located at substantially all sides of theimage generating means (a liquid crystal display 12). The imagedirecting means comprises an array of substantially spherical lenses 42overlying the display 12. The lenses are convex and can potentiallydirect the light from the pixels below in any direction. The actualdirection in which a lens directs the received light depends upon theposition of each pixel below relative to the lens and on the shape ofthe lens curvature.

In this embodiment, each substantially spherical lens overlies a threeby three matrix of pixels, with the central pixel of the nine pixelsbeing directed in a forward direction. Four pixels, one in each of thecentre of each side, are directed toward their respective nearest sideof the display 12. The four corner pixels of the matrix of nine aredirected in at an angle halfway in-between that of the paths travelledby the adjacent centre-side pixels. In this way an effective image 44 isprovided that is larger than the original image from the display 12, butalso covers an area that extends out from the original display 12 in alldirections (in the plane of the display 12). Reflections through twomirrors are used to create viewing zones occupying the corners of thevirtual viewing space.

An alternative arrangement to the array of substantially sphericallenses 42 shown in FIG. 5, is to have a lens arrangement that comprisesan array of hexagonally packed lenses that are still nevertheless eachsubstantially spherical.

FIG. 7 show a section through another embodiment of the image generatingmeans and image directing means, where they comprise an array ofdirectional light sources 50 that replaces the display and lens arraysof the previous embodiments. The array 50 transmits light in a number ofdifferent directions from the channels 52 as shown by the arrows. Inthis way light can be generated to travel in a forward direction for thecentral part of the resulting virtual image and light can be suitablydirected at the mirrors as desired in order to create the side portionsof the effective image. A number of modifications of this embodiment arepossible, including having channels 52 that are conical with a divergingmouth to provide a cone of light. The number of channels can beincreased to provide light travelling in more than three differentdirections, to increase the size of the effective image, or to provide a3D effective image.

Other known directional means for directing the light include a parallaxbarrier system, an array of holographic elements, a collimating system,a pinhole arrangement, interference filters, and prisms.

In another embodiment (not shown) the image directing means operates bytime multiplexing a single pixel in different directions. Each pixeltherefore provides the light necessary for each part of the effectiveimage in turn and the image directing means has a duty cycle scheme thatdirects the emitted light at the different portions of the imagereflecting means, in turn.

In yet a further embodiment the image directing means directs a portionof the light from the pixels at an angle of incidence that is muchcloser to the horizontal than that shown in FIG. 2. The result of thisis that the light is reflected by the mirror 16 across to the secondelement of the mirror 16 on the opposite side of the display 12, andthen reflected out for adding further to the effective image. Thiscreates an even larger effective image, with the light that is reflectedtwice being visible beyond the edge of the light that is reflected once.

In another embodiment, the pitch of the lenticular lens array 14 isslightly larger than the pitch of two pixels, with the result that thelens array 14 is not directly aligned with the pixels underneath overthe whole of the width of the display 12. In the centre of the display12 the lenses are substantially aligned with the pixels underneath, buton either side of the centre each lens is offset to a degree, whichincreases progressively towards the edge of the display 12. In thisembodiment only columns of two pixels are used to create the effectiveimage 18 which will have side portions of the effective image 18 eachequal to half of the size of the original image. The resolution of theeffective image 18 is half that of the original image.

In a still further embodiment, the pitch of the lens array 14 is thesame as the pitch of the pixels in the display 12, but the lens array 14is not necessarily aligned exactly with the pixels underneath. In thiscase the software controlling the pixels adapts to the difference inalignment to correct the difference.

Further refinements of the apparatus are possible, including the use ofstandard ranging techniques to make the effective image appear to comefrom a greater distance than the physical screen. This is to facilitatepeering into the display at close range. The directing of the light canbe taken advantage of to produce a three-dimensional effective image, byincluding in each portion of the effective image at least two views, onefor each eye. Where the effective image is produced on a visual displayunit, the associated processor and software can be arranged so that amouse or pointing device can be used to select a point or portion of theeffective image that is outside the normal physically constraineddisplay. The apparatus for producing the effective image can be used ona wide range of display devices, including PDAs, remote control devices,televisions, monitors, dashboard displays, head mounted displays etc. Inthe case where the apparatus is a dashboard display, the windscreen canact as the image reflecting means. A suitably placed display with alenticular overlay can show one set of information when directly lookedat, and another when a user looks at the display via the reflection inthe windscreen.

1. Apparatus for displaying an image comprising image generating means,image directing means for directing a first portion of the image in afirst direction and for directing a second portion of the image in asecond direction, and image reflecting means for reflecting at leastsome of said second portion, operable to produce an effective imagelarger than said image generating means.
 2. Apparatus according to claim1, wherein said image generating means comprises a liquid crystaldisplay.
 3. Apparatus according to claim 1, wherein said imagegenerating means comprises an array of light emitting diodes. 4-9.(canceled)
 10. Apparatus according to claim 1, wherein said imagereflecting means comprises a mirror.
 11. Apparatus according to claim 1,wherein said apparatus is a mobile communication device.
 12. Apparatusaccording to claim 1 wherein said apparatus is a visual display unit.13. A method for displaying an image comprising generating an image,directing a first portion of the image in a first direction, directing asecond portion of the image in a second direction, and reflecting atleast some of the second portion to produce an effective image largerthan the generated image.
 14. A method according to claim 13, whereinsaid generating an image is provided by a liquid crystal display or anarray of light emitting diodes.
 15. A method according to claim 13,wherein said directing is provided by a lens arrangement.
 16. A methodaccording to claim 13, wherein said reflecting is provided by a mirror.17. The apparatus of claim 1, wherein the first portion of the imageforms a central portion of the effective image, and the second portionof the image forms a side portion of the image adjacent the centralportion.
 18. The apparatus of claim 1, wherein the first direction issubstantially normal to a top surface of the image generating means. 19.The apparatus of claim 1, wherein the image generating means comprises aplurality of pixels, and wherein the image directing means directs lightfrom a single pixel in the first direction during a first time periodand directs light from the single pixel in the second direction during asecond time period subsequent to the first time period.
 20. The methodof claim 13, wherein the first portion of the image forms a centralportion of the effective image, and the second portion of the imageforms a side portion of the image adjacent the central portion.
 21. Themethod of claim 13, wherein the first direction is substantially normalto a top surface of an image generating means generating the image. 22.The method of claim 13, wherein directing the first portion of the imagein a first direction comprises directing light from a first pixel in thefirst direction during a first time period and directing a secondportion of the image in a second direction during a second time periodsubsequent to the first time period.
 23. An apparatus for displaying animage, comprising: a display device adapted to generate an image; imagedirecting means for receiving the image and for directing a firstportion of the image in a first direction, and for directing a secondportion of the image in a second direction forming an angle with respectto the first direction; and a reflecting device adapted to receive thesecond portion of the image, and to reflect at least a part of saidsecond portion in a third direction to form an effective image having asize larger than a size of the display device.
 24. The apparatus ofclaim 23, wherein the first portion of the image forms a central portionof the effective image, and the second portion of the image forms a sideportion of the image adjacent the central portion.
 25. The apparatus ofclaim 23, wherein the first direction is substantially normal to a topsurface of the display device.
 26. The apparatus of claim 23, whereinthe display device comprises a plurality of pixels, and wherein theimage directing means directs light from a single pixel in the firstdirection during a first time period and directs light from the singlepixel in the second direction during a second time period subsequent tothe first time period.